385 research outputs found

    Leading Edge Boundary Layer Suction Device for the Cal Poly Rolling Road Wind Tunnel

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    Over the course of three quarters from Fall of 2016 to Spring of 2017, our team designed and built a boundary layer suction device. The boundary layer suction device has three main functions: a scoop that redirects most of the boundary layer air out of the wind tunnel, fans that suck the remaining boundary layer air through a porous plate and ducting and out of the wind tunnel, and a transition bridge that transitions the remaining air smoothly onto the rolling road. The wind tunnel is owned by Cal Poly and the rolling road is a new addition to it. By the end of our project, the rolling road was not yet functional. A variable-frequency drive (VFD) will be installed over the summer and belt suction fans will also be installed. Once these are in place, the rolling road can be used. We were successful in building our device and installing it, but once the rolling road is functional, further iterations can be made on our device. The framing and ducting will likely stay in place without further iterations. However, which fans are used can be changed around. We designed our device with an American Fan model AF-10 in mind, but this fan cannot be used until the VFD is installed. There are other fans that can be repurposed and tested on this device as well, though. And, if necessary, a more powerful fan could be purchased. The lid, consisting of the scoop, porous plate, and transition bridge, was also designed to be flexible enough for further iterations. All three of its components are separate pieces that fasten to each other and the lid itself is separate from the rest of the assembly and is only meant to attach to it during tests. Two issues could crop up with the scoop: less air than expected being redirected through the scoop, and the scoop creating flow separation. If the latter issue occurs, a new scoop could be made with the angle (currently 10 degrees) reduced. If the former issue occurs, a new scoop could be made with longer overhang, or ducting could be made from where the flow is redirected, to the end of the tunnel. The following report details the process we went through to make this device. It provides details on the design process, final design analysis, manufacturing results, and test plans that show our progress from project ideation all the way to design acceptance and verification

    THE ANTAGONIST MUSCLE PATTERN IN ELBOW EXTENSION OFA THROWING TASK

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    INTRODUCTION The myoelectric activity in fast human movements is characterised by a phasic pattern with two fundamental events: the first agonist burst, responsible for the initial limb acceleration, and an antagonist impulse. The accurate definition of the antagonist burst role, and the relative participation of peripheral and central sources on its control, are not clearly defined in the literature (Angel, 1977; Marsden et al., 1983). The purpose of the present study was (1) to characterise the antagonistic pattern on the elbow extension when subjects had to throw a dart onto a target, and (2) to analyse the antagonist changes when subjects throw with different accuracy/speed demands. Experiments were performed on 13 subjects. Surface EMG were recorded from triceps and biceps brachii with active bipolar electrodes. Electrogoniometers wore used on shoulder and elbow joints. RESULTS The antagonist EMG contained a phasic burst (ANT) which began between the movement onset and the end of the agonist activation, with an usual co-contraction duration of less than 30 ms. The time interval between the movement onset and the beginning of ANT was normally higher than the EMG latency necessary for spindle influences, considered to be less than 20 ms (Tarkka, 1986). In our results, ANT always began during the acceleration phase and, in most cases, developed its maximum intensity around the moment of elbow peak velocity. So, the antagonist burst represents more than an impulse braking preventing full extension, and we must admit its participation in the control of the duration of the acceleration phase. Antagonist modifications with velocity indicated an amplitude increase, measured by the integrated EMG. without relevant temporal changes. Two subjects presented an alternative way of braking the movement, when the accuracy constraints were absent, based, on the increase of the joint stiffness through the co-contraction of agonist and antagonist muscles. This kind of movement braking resulted in a reduced timing accuracy demand when compared with the active braking, produced by the antagonist phasic burst (Ghez & Martin, 1 982). CONCLUSION The timing of the antagonist phasic burst invite us (1) to associate it with the control of the end of the acceleration phase and (2) to accept that it could be influenced by the muscular response to stretch, although modulated by higher central commands. (3) The general tendency was to maintain the temporal structure of antagonist EMG among conditions and to increase its intensity with the increase of the throwing velocity. (4) Two subjects presented an alternative way of braking the movement when the accuracy constraints wers absent. REFERENCES Angel, R. (1977). Antagonist muscle activity during rapid arm movements. Central versus proprioceptive influences. J. Neuroi, Neuros., Psychia t., 40: 683-686. Ghez, C., & Martin, J. (1 982). The control of rapid limb movement in the cat. Ill - Agonist- Antagonist coupling. Exp: Br. Res., 45: 1 15 - 125. Marsden, C., Obeso, J., & Rothwell, J. (1983). The function of the antagonist muscle during fast limb movements in man. J. Physiol., 335: 1 - 13. Tarkka, 1. (1986). Short and long latency reflexes in human muscles following electrical and mechanical stimulation. Acta Physiol. Scand., 128. Supplem. 557: 1-32

    Electron Microprobe Analysis and Proton Induced X-Ray Spectrometry Applied to Trace Element Analysis in Sulfides: Problems and Prospects

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    The complementary techniques of EPMA and micro-PIXE are reviewed in the context of spatially resolved trace element analysis of sulfide minerals. Attention is focussed on methods of standardization and of fitting EDX spectra. Sphalerites and chalcopyrites from various sources are used as specimens. For Ag in chalcopyrites, the two techniques agree well. Sphalerites pose problems such as Zn-Fe replacement and the presence of minor elements, both of which influence matrix corrections ; these are addressed in detail. The necessity for absorbers in the micro-PIXE work prevents detection of minor elements lighter than Zn ; these are determined by EPMA and the results used in the micro-PIXE fitting and matrix corrections. For Cd, Ag, Ga, Ge there is acceptable agreement between the two techniques given uncertainties and constraints on samples, but EPMA results for Hg are notably lower than micro-PIXE results. The improvement in detection limits afforded by micro-PIXE over EPMA in these sulfide minerals ranges from ~ 3 for Ga, Ge, Hg to 10-30 for Se, Ag, Cd, In ; possible further gains are discussed for both techniques

    Impact of Combined Exercise on Chronic Obstructive Pulmonary Patients' State of Health

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    AIM: The aim of the study was to evaluate the effectiveness of a 10-week combined training programme (aerobic and strength exercise) compared to an aerobic training programme, and respiratory physiotherapy on COPD patients' health. METHODS: Fifty subjects with moderate to severe COPD were randomly assigned to two groups. Combined group (CG, n=25) who underwent combined training, and aerobic group (AG, n=25) who underwent aerobic training. These were compared with fifty COPD subjects who underwent respiratory physiotherapy, breathing control and bronchial clearance techniques (RP group, n = 50). We evaluated health state through two questionnaires, St. George's Respiratory Questionnaire (SGRQ) and SF-36, at the beginning and at the end of the programme. RESULTS: The CG group showed differences (p<0.0001) in modification rates in state of health compared to the AG and RP groups in the activity (64 ± 9%, 19 ± 7%, 1 ± 15%) , impact (35 ± 5%, 20 ± 18%, 1 ± 14%) and total (41 ± 9%, 26 ± 17%, 1 ± 15%) domains assessed by the SGRQ, and the physical function (109 ± 74%, 22 ± 12%, 0.1 ± 18%), physical role (52 ± 36%, 11 ± 15%, 1.3 ± 21%) and vitality (83 ± 39%, 14 ± 38%) domains assessed by SF-36. CONCLUSION: These results suggest that combined training in subjects with COPD appears to be a more effective method, with better clinical changes, and improvements in health state perception

    Electromyographic Analysis of the Dominant Upper Limb During the Golf Swing

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    Purpose: The identification of neuromuscular patterns is an important cue for the management of muscular development, skill improve- ment and injury prevention. The main purpose of the present study was to characterize muscular coordination patterns in the dominant upper limb in the different phases of golf swing in experienced golfers. Methods: Three low-handicap golfers (handicap lower than five) performed six full swing movements with a pitch iron. Surface electro- myography (EMG) was recorded from 12 muscles: anterior (AD), middle (MD) and posterior (PD) deltoids, pectoralis major (PM), latissimus dorsi (LD), infraspinatus (IS), vastus lateralis (VL) and long portion (LP) of triceps brachii, biceps brachii (BB), brachioradialis (BR), wrist flexors (WF), and wrist extensors (WE). The EMG signals were sampled at 1000 Hz, full wave rectified, low pass filtered (second order Butterworth filter at 12 Hz) and normalized using the EMG of the maximal voluntary contraction (MVC) as a reference. In synchrony with the EMG signals, a three axis accelerometer fixed at the back of the golf club head informed about ball contact time (BC). Mean EMG value was calculated separately during each phase: backswing (BS), downswing (DS) and the first 500 ms of the follow-through (FT). For the move- ment analysis and phase delimitation the swing was filmed with four high speed video cameras (300 Hz). The recording of EMG and cinematic data was performed with a SIMI system (SIMI Motion, Munich, Germany). Results: The average of normalized values of all muscles of the dominant arm in the three subjects, showed that the DS exhibited the highest muscular activity (28,8% of the EMG of the MVC) compared with the FT (19,9%) and the BS (15,7%). The elbow flexors (BB 26%, BR 45%) and the wrist extensors (WE 26%) presented the strongest activation during the BS to promote elbow flexion and hand extension, and silenced before the DS initiation. During the DS the shoulder adductors (LD 53%, PM 38%) and the elbow extensors (LP 50%, VL 47%) presented the highest EMG activation. These muscles were activated at the beginning of the DS but the shoulder adductors peaked earlier. The AD peaked 70 ms before the BC and its activation may contribute to the arm internal rotation during the acceleration phase. The WF peaked during or just after the BC to accelerate hand flexion. The shoulder abductors (AD 34%, MD 14%) and the wrist flexors (36%) showed the highest activity during the FT. The posterior and middle deltoids showed low activity in all the phases (less then 20%). Conclusions: The results demonstrated that the most active muscles during the golf swing were the shoulder adductors and the elbow extensors, and that the downswing was the phase where muscles from the dominant upper limb presented stronger activation. The EMG patterns we found can help to design training programs to improve strength and flexibility and to reduce injury risk in the golfers upper limb

    Biomechanical predictors of ball velocity during punt kicking in elite rugby league kickers

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    Punt kicking is integral to the attacking and defensive elements of rugby league and the ability to kick the ball with high velocity is desirable. This study aimed to identify important technical aspects of kicking linked to the generation of ball velocity. Maximal punt kicks were obtained from six elite rugby league kickers using a 10-camera motion capture system. Three-dimensional kinematics of the lower extremities was obtained. Regression analysis with ball velocity as criterion was used to identify the kinematic parameters associated with the development of ball velocity. The regression model yielded an adj R2¼0.76, p�0.01. Two parameters were identified: knee extension angular velocity of the kicking limb at impact (R2¼0.50) and peak flexion angular velocity of the kicking hip (R2¼0.26, p�0.01). It is conceivable that players may benefit from exposure to coaching and strength techniques geared toward the modification of kicking mechanics specific to this stud

    Methodological Guidelines for Engineering Self-organization and Emergence

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    The ASCENS project deals with the design and development of complex self-adaptive systems, where self-organization is one of the possible means by which to achieve self-adaptation. However, to support the development of self-organising systems, one has to extensively re-situate their engineering from a software architectures and requirements point of view. In particular, in this chapter, we highlight the importance of the decomposition in components to go from the problem to the engineered solution. This leads us to explain and rationalise the following architectural strategy: designing by following the problem organisation. We discuss architectural advantages for development and documentation, and its coherence with existing methodological approaches to self-organisation, and we illustrate the approach with an example on the area of swarm robotics

    Rare-metal granites as a potential source of critical metals: A geometallurgical case study

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordBecause of their low grades in critical metals such as Light Rare Earth Elements (LREE) or Sn, rare-metal granites are not considered as economic for metal recovery but, when altered, they are often exploited for their industrial minerals. The St Austell rare-metal granite is well known for its world-class kaolin deposits which formed as a result of the extensive weathering and alteration of the underlying granite. The St Austell granite body is composed of several granite components, each having its own accessory minerals assemblage. As a result of the kaolinisation process, some metal-bearing accessory minerals of the granite, such as monazite (LREE) or cassiterite (Sn), are partially liberated from the gangue which allow their pre-concentration in the micaceous residue which is considered as a potential source for critical metals recovery. Similarities with other similar rare-metal granites suggest that topaz granite is the most prospective for disseminated magmatic Sn-Nb-Ta-REE mineralization. However, comparison of the potentiality of 3 granite types i.e., biotite, topaz and tourmaline granites suggest that biotite granites is actually the most prospective due to higher degree of kaolinisation of the biotite granite which favour pre-concentration of its accessory mineral in the micaceous residue. In order to develop a geometallurgical framework for extraction of kaolin and metals from the selected granite component, a field sampling campaign is performed. Core samples are processed in the laboratory using a characterisation program that mimics the full-scale kaolin refining route. Two main products are recovered through this program, viz. MR180 (−180 +53 µm) and P5 (−5 µm), which correspond to a fine micaceous residue and a fine kaolin product respectively. These products are both analysed routinely for major and minor trace elements by XRF and yields are recorded to indicate process performance. A selected number of MR180 samples are also being characterised in terms of particle size by laser light scattering, geochemistry by ICP-MS, and mineralogy by QEMSCAN®. Comparison of characterisation results of MR180 samples and corresponding industrial residue samples shows a good correlation, suggesting that sample analyses are representative for the in-situ deposit and the processing behaviour. Monazite is found to be either fully liberated or fully locked from one sample to the other. Next, pilot-scale gravity concentration tests are performed on micaceous residue samples. Characterisation of the processing products shows that monazite lost in the tailings is mostly locked within tourmaline or micas and is fine grained. Then, predictive regression models for spiral separation performance in terms of recovery, product grade and enrichment as a function of the feed grade are developed for MR180 LREE grade data. Finally, kaolin resources can be classified using quantitative indicators such as yield of the P5 product and the iron oxides content which provides insight into the kaolin quality in terms of whiteness. This geometallurgical classification can be used to delineate zones of interest within the deposit. Although kaolin quality and recovery primarily inform extraction planning, zones which are also of interest for metal recovery can be identified. The proposed model predicts whether the expected LREE grade and recovery satisfy the by-product requirements.European CommissionNatural Environment Research Council (NERC)French National Research Agenc

    Reliability and validity of PedsQL for Portuguese children aged 5–7 and 8–12 years

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    BACKGROUND: Pediatric Quality of Life Inventory (PedsQL) is a measure to assess health-related quality of life (HRQoL) in children and adolescents. It is formed by 23 items adapted to children age and includes a parent proxy report version. With four multidimensional subscales and three summary scores, it measures health as defined by WHO. The concepts measured by this instrument are ‘physical functioning’ (8 items), ‘emotional functioning’ (5 items), ‘social functioning’ (5 items) and ‘school functioning’ (5 items). It also measures a ‘total scale score’ (23 items), a ‘physical health summary score’ (8 items) and a ‘psychosocial health summary score’ (15 items). The aim of this paper is to present the main results of the cultural adaptation and validation of the PedsQL into European Portuguese. METHODS: The Portuguese version was the result of a forward-backward translation process, with a cognitive debriefing analysis, guaranteeing face validity and semantic equivalence. Children aged 5–7 and 8–12 were randomly selected and were asked to fill a socio-demographic data survey and the Portuguese versions of PedsQL and KINDL, another HRQoL measure for children and adolescents. They were divided into three groups, healthy children, children with type I diabetes and children with spina bifida. The reliability was tested for reproducibility (ICC) and internal consistency (Cronbach’s alpha). The construct validity (known-groups discriminant validity) was supported by differences between self-reports from healthy children and children with chronic conditions, and from children with chronic diseases and their parents. The criterion validity was tested after the correlations of the scores obtained by both children and adolescents HRQoL assessment instruments. RESULTS: A total of 179 children and 97 parents were recruited. PedsQL demonstrated good levels of reproducibility (r > 0.95 in all versions) and acceptable levels of internal consistency with Cronbach’s alpha at 0.70 on most scales. Concordance values between children’s and parents’ perceptions ranged between 0.36 and 0.78 and the correlations with KINDL questionnaire were excellent, supporting concurrent validity. CONCLUSIONS: The Portuguese version of the PedsQL demonstrated acceptable psychometric properties for future research and clinical practice for children aged 5–12
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